Dendrite-free deposition and side-reaction suppression of zinc anodes achieved via constructing synergistic interface buffer layers

Abstract

Aqueous zinc metal batteries (ZMBs) are expected to be used in grid-scale storage systems due to their superior intrinsic safety and the low manufacturing cost of zinc anodes. However, uncontrolled dendrite deposition and side-reaction pose challenges to the durable operation of ZMBs on a large scale. Herein, we construct a bifunctional buffer layer for zinc anodes (δ-MnO₂@Zn), aiming to achieve dendrite-free deposition and side-reaction suppression of zinc anodes that are suitable for large-scale use. Density functional theory calculations and electric field simulations revealed that the δ-MnO₂ coating facilitates the desolvation of Zn²⁺ and promotes uniform diffusion and deposition of Zn²⁺ on the Zn anode surface. In addition, the porous δ-MnO₂ coating acts as a physical buffer layer, and can reduce rampant dendrite deposition by regulating the Zn²⁺ concentration field and reducing the local current density. Furthermore, the zincophilic δ-MnO₂ coating acts as a chemical buffer layer, reducing the amount of bound water in the Zn²⁺ solvent shell and inhibiting unfavorable side-reaction of the Zn anode. As expected, the δ-MnO₂@Zn symmetric cell demonstrates a lifespan of more than 1000 h at a rate of 0.5 mA cm⁻² with 0.25 mA h cm⁻². Moreover, the full battery assembled with a carbon-based cathode demonstrated outstanding cycling behavior of over 11 500 cycles at 2 A g⁻¹. The conclusions demonstrate the principle of a synergistic interfacial buffer layer on the Zn anode surface, guiding the development of advanced artificial interface layers.